Infections caused by pneumococci are a major cause of morbidity and mortality all over the world. Pneumonia, febrile bacteraemia and meningitis are the most common manifestations of invasive pneumococcal disease, whereas bacterial spread within the respiratory tract may result in middle-ear infection, sinusitis or recurrent bronchitis. Compared with invasive disease, the non-invasive manifestations are usually less severe, but considerably more common.
The etiological agent of pneumococcal diseases, Streptococcus pneumoniae (pneumococcus), is a Gram-positive encapsulated coccus, surrounded by a polysaccharide capsule. Differences in the composition of this capsule permit serological differentiation between about 91 capsular types, some of which are frequently associated with pneumococcal disease, others rarely. Invasive pneumococcal infections include pneumonia, meningitis and febrile bacteremia; among the common non-invasive manifestations are otitis media, sinusitis and bronchitis.
Pneumococcal conjugate vaccines (PCVs) are pneumococcal vaccines used to protect against disease caused by S. pneumoniae (pneumococcus). There are currently three PCV vaccines available on the global market: PREVNAR® (called Prevenar in some countries) (heptavalent vaccine), SYNFLORIX® (a decavalent vaccine) and PREVNAR 13® (tridecavalent vaccine).
The specific serotypes causing disease beyond the 13 in PREVNAR 13® vary by region, population, and may change over time due to acquisition of antibiotic resistance, pneumococcal vaccine introduction and secular trends of unknown origin.
The addition of conjugates to an immunogenic composition is not a straightforward process as the combination of conjugates into a single multivalent injection may result in competition among the different components and may adversely affect the immunogenicity of any individual conjugate.
This phenomenon of interference may limit the number of conjugates which can be included in a multi-valent vaccine. Therefore protection against a high number of serotypes, while limiting the number of conjugates in the composition, maybe very difficult to obtain despite of the significant value.
An object of the present invention is to provide immunogenic compositions for appropriate protection against S. pneumoniae, in particular against S. pneumoniae serogroup 9, while limiting the number of conjugates.
Streptococcus pneumoniae serogroup 9 consists of four different types, 9V, 9A, 9L, and 9N, each of which produces its own, type-specific capsular polysaccharide (Richards, J. C and M. B. Perry, 1988, In A. M. Wu (ed.), The molecular immunology complex carbohydrates. Plenum, N.Y., pp. 593-594).
It is an object of the present invention to provide immunogenic compositions for appropriate protection against S. pneumoniae serotypes 9V, 9A, 9L, and 9N, with a limited number of conjugates.